This application claims priority from Korean Patent Application No. 2003-54343, filed on Aug. 6, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a plasma display panel sustain driver and, more particularly, to a plasma display panel sustain driver having a decreased flywheel current that is generated when a plasma display panel is driven.
2. Description of the Related Art
A plasma display panel displays characters or images using plasma that is generated by gas discharge. A plasma display panel sustain driver is used to drive the plasma display panel.
FIG. 1 is a circuit diagram of a plasma display panel sustain driver 101 connected to a plasma display panel 111, disclosed in U.S. Pat. No. 4,886,349. Referring to FIG. 1, the plasma display panel sustain driver 101 includes a capacitor Cc, MOS transistors Sr, Sf, Su and Sd, diodes Dr, Df, D1 and D2, and an inductor L. A terminal 121 is connected to another plasma display panel sustain driver (not shown).
The plasma display panel sustain driver 101 operates in four modes M1, M2, M3 and M4. The waveform of a voltage Vp applied to the plasma display panel 111 and the waveform of a current iL flowing through the inductor L for the four modes M1, M2, M3 and M4 are shown in FIG. 2. As shown in FIG. 2, large flywheel currents if1 and if2 flow through the inductor L in the second and fourth modes M2 and M4, respectively.
The flywheel current if1 flows from the MOS transistor Su to the diode D1 through the inductor L when the MOS transistor Su is turned on in the second mode M2. The flywheel current if2 flows from the diode D2 to the MOS transistor Sd through the inductor L when the MOS transistor Sd is turned on in the fourth mode M4.
The MOS transistors Su and Sd are placed under high current stress because of the large flywheel currents if1 and if2. Thus, the MOS transistors Su and Sd should have high current specifications. It the MOS transistors Su and Sd have high current specifications they are relatively large in physical size, resulting in an increase in the size and cost of the plasma display panel sustain driver 101.
Furthermore, between of the large flywheel currents if1 and if2, the power consumption of the MOS transistors Su and Sd is large. Thus, the power consumption of the plasma display panel sustain driver 101 is also large.
FIG. 3 is a circuit diagram of a plasma display panel sustain driver 301 connected to a plasma display panel 311, which is disclosed in U.S. Pat. No. 5,828,353. Referring to FIG. 3, the plasma display panel sustain driver 301 includes a capacitor Cc, MOS transistors Sf, Sr, Su and Sd, diodes Df, D11, D12, Dr, D21, D22, Du and Dd, and inductors L1 and L2. A terminal 321 is connected to another plasma display panel sustain driver (not shown).
The operation of the plasma display panel sustain driver 301 is similar to that of the plasma display panel sustain driver 101 shown in FIG. 1, and the waveforms of a voltage Vp applied to the plasma display panel 311 and a current flowing through the inductors L1 and L2 are similar to those shown in FIG. 2.
Flywheel currents (if1 and if2 in FIG. 2) are generated by the inductors L1 and L2 and they cause high current stress in the MOS transistors Su and Sd. Accordingly, the size and cost of the plasma display panel sustain driver 301 are remarkably increased and the power consumption of the panel is also increased.
FIG. 4 is a circuit diagram of a plasma display panel sustain driver 401 connected to a plasma display panel 411, which is disclosed in Japanese Patent No. 2002-62843A. Referring to FIG. 4, the plasma display panel sustain driver 401 includes MOS transistors Sr, Sf, Su1, Su2, Sd1, Sd2, Sa and Sb, diodes Dr, Df, D11, D12, D21, D22, D31, D32, Da and Db, capacitors Cd and Cd, and inductors Lr and Lf. A terminal 421 is connected to another plasma display panel sustain driver (not shown).
The plasma display panel sustain driver 401 operates in six modes M1 through M6. The waveform of a voltage Vp applied to the plasma display panel 411 and the waveform of currents iLr and iLf flowing through the inductors Lr and Lf for the six modes M1 through M6 are shown in FIG. 5. As shown in FIG. 5, large flywheel currents if1 and if2 flow through the inductors Lf and Lr in the second and fifth modes M2 and M5, respectively.
The flywheel current if1 flows from the MOS transistor Su2 to the diode D21 through the inductor Lr when the MOS transistor Su2 is turned on in the second mode M2. The flywheel current if2 flows from the diode D22 to the MOS transistor Sd2 through the inductor Lf when the MOS transistor Sd2 is turned on in the fifth mode M5.
The MOS transistors Su2 and Sd2 are placed under high current stress because of the large flywheel currents if1 and if2. Accordingly, the size and cost of the plasma display panel sustain driver 401 are increased and its power consumption is also increased.